24-Hour Free Protein Urine Test (Mass Fraction)
This test measures the total amount of protein that appears in your urine over a 24-hour period, excluding proteins bound to other substances.
["Assesses kidney function by detecting protein loss in urine over a full day."]
Key facts at a glance
- LOINC
- 101179-0
- Short code
- FLCU24
- Synonyms
- BJ Protein Free 24h MFr Ur
- Category
- chemistry
- Sample
- urine
- Container
- 24-hour urine collection container without preservatives (or with appropriate preservative per laboratory protocol); sterile aliquot container for transport
- Units
- N/A
- Ref low
- 1
- Ref high
- 7
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Immunonephelometry / Immunoturbidimetry for free light chains; Biuret or turbidimetric method for total protein
- CPT
- 83883
- SNOMED
- 313919003
- Specimen volume
- Complete 24-hour urine collection; minimum 10 mL aliquot for testing
- Stability
- Ambient: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test to check for kidney disease, monitor kidney function, or evaluate conditions like nephrotic syndrome, where the kidneys release unusually high amounts of protein into urine. It can also help track how well treatments are working for kidney-related issues.
How the Test Works
You’ll collect all urine produced in a 24-hour period in a special container. The collected urine is then analyzed to determine the total protein content, excluding proteins that are naturally present in urine but not lost through kidney dysfunction.
Sample Collection Process
Start by emptying your bladder at the beginning of the 24-hour period. Use a clean container to collect all urine for the next 24 hours, including during sleep. Replace the container daily if needed. Finish by collecting your final urine sample at the end of the 24 hours and send it to the lab with the container.
What to Expect After the Test
After collection, the lab processes your urine sample to measure free protein levels. Results are typically reported as a total protein amount over 24 hours. Follow-up instructions from your doctor will guide next steps based on your results.
Reference range
Free light chain ratio (kappa/lambda) in urine: typically reported alongside 24-hour total urine protein excretion. Normal 24-hour urine protein: <150 mg/24 hours. Free kappa: 1.0-7.0 mg/L; Free lambda: 0.8-5.0 mg/L (laboratory-specific).N/A
No fasting required. Maintain normal hydration unless otherwise instructed. Patient should follow standard 24-hour urine collection protocol. Avoid strenuous exercise prior to and during collection period.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
24h Free Protein Urine
Frequently asked questions
What Does a High or Low Result Mean?
How Often Should I Get This Test?
Can I Eat or Drink Normally While Collecting Urine?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy